In New England the first slaves were native Americans, captured as war prisoners during the conflicts between the indigenous population and European settlers. [1]
The practice of enslaving captured peoples was well-established among the native population. In 1638, New Englanders began to import Africans, initially by exchanging native Americans captured in the Pequot War for black slaves in the West Indies. In 1638, William Pierce, a Boston ship captain, took several captive Pequot Indians to the West Indies to sell into slavery. In exchange for these captives, Pierce brought back salt, cotton, tobacco, and Africans. [2]

The commerce in slavery was revived on a much greater scale in the aftermath of King Philip’s War in the 1670s. Initially New Englanders drew a distinction between purchasing enslaved Africans and actually trafficking in the slave trade. By the end of the seventeenth century, that distinction was lost and Massachusetts ships began to embark for West Africa on the quest for Africans to sell in the trade.

The Pequot Indians of central Connecticut attacked the town of Wethersfield in 1637. A few months later, Massachusetts and Connecticut militia and their Narragansett Indian allies fell upon the Pequot village near Mystic, Connecticut. Only a few Indians escaped the slaughter. The women and children were enslaved in New England, and the men and boys were carried to the West Indies and sold into slavery. Captain Underhill was the commander of the Massachusetts forces in this war and led the storming of the fort.

John Winthrop. A journal of the transactions and occurrences in the settlement of Massachusetts and the other New England colonies, from the year 1630 to 1644. (Hartford: Elisha Babcock, 1790).

John Winthrop (1588–1649), first governor and chronicler of Massachusetts Bay, wrote a manuscript history of New England, which contains references to the first Africans imported to the region. The original manuscript is at the Massachusetts Historical Society. Noah Webster first published a rather corrupt and incomplete transcription of it in 1790 (shown here). The passage in question occurs under an entry dated December 26, 1637:

Mr. Pierce in the Salem ship, the Desire, returned from the W. Indies after seven months. He had been at Providence and brought some cotton and tobacco and negroes &c, and salt from Tertugos [Tortuga]. Dry fish and strong liquors are the only commodities for those parts. He met there two men of war set forth by the Lords &c. of Providence, with letters of marque who had taken divers prizes from the Spaniards, and many negroes.